<div class='quotetop'>QUOTE(gsfan @ Nov 10 2007, 05:29 AM) [snapback]100054[/snapback]<div class='quotemain'>
The desmo system is simply a system that Ducati uses and promotes. It is not the only system of 19k+ operations. The beauty of pneumatics is that the oscillation rate of nitrogen is in the 100k Hz range meaning no valve floating ever. The pressure of the cylinders can be as low as 40psi so little friction is created against the cams. Suzuki developed their valve system on the track and after 13 blown engines in Qatar a year and a half back have had no problems at all. So I suspect this is the system standard now. Honda for sure had a motor that was too big bang this was the biggest problem. You could hear the chang chang chang when it left the pits. For sure they have a screamer which will be able to spin and make huge power.
The Ducati's main strength was the fact that it was less of a big bang engine if you ask me. Instead of using the engine mechanics to optimize power delivery they used software. Honda is now following suit. With the massive low frequency power pulses trying to pull the case apart now gone all the engine internals can be lighter making for faster acceleration rates. 20mm strokes and high revs mean a shrieking power plant. That is exactly what Honda now has so the power problem is gone. Just tires now. BTW an L engine is a true 90 degree engine which likely no team runs since it would be too long.
Nice analysis gsfan.
One key advantage of desmo is not so much being able to run at 19k and more, (they say Ducati can reach 22k without blowing up, even if it is not pushed that far in any racing configuration) but rather the fact that valve operation uses only the necessary amount of power at each rpm speed. This gives it more power in the low and mid ranges (=acceleration).
Springs is the worst because even at low rpm the engine has to compress some really hard springs necessary to close the valves fast enough at high rpm. I do not know how much work the pneumatic system uses to operate, I imagine it should be halfway between springs and desmo. Desmo is imo hard to beat in this area as it does not have to compress anything to operate the valves, be it springs or air... It just has to push along the valvetrain and rocker arms' inertia, and with today's materials these small components can be very light.
Another key advantage is the so called 'square' valve diagram, meaning basically the valves can remain safely open as long as possible without being hit by the piston, as their recyprocal movements are mechanically linked. Springs can never approach a square waveform because the springs take time to compress and release, generating a synusoidal waveform. Here too, I imagine pneumatic systems should improve a lot on the spring system, but not really reach the desmo perfect 'squareness'. The advantage of this squareness is better 'breathing', which means better efficiency not only for power but also for fuel (and in fact Ducati has not suffered as the others with the 21-liters rule this year).
As I said, what I do not know is how close the pneumatic system can come to the desmo in these areas. You seem to know better. It should be pretty close, but not actually same. Probably close enough to make the desmo advantages irrelevant in a race.
I agree with you the desmo is an ideal 'screamer' solution, coupled with the right electronics and rubber to transfer power to the ground (and with the right rider too I must add, - so far only an Australian boy has been capable to tame it!). Capirossi preferred to continue to use the big-bang for most of the season, it seems, and that would explain something.
Anyway the 800cc/21 liters formula has really given Ducati a boost! The desmo advantages were almosrt irrelevant with the 990cc, when everybody was using big bang configurations without problems, as every engine had power to burn...
